Why Is My Check Engine Light On?

One experience that most drivers dread is looking at their dashboard and seeing their check engine light illuminated. This small light, which typically is yellow, orange, or red in color and the shape of an engine, signals that there’s something wrong with your vehicle’s operations. While your first instinct may be to feel stressed, it’s important to know how to respond to this situation appropriately. Our team at AutoCenters Herculaneum created this guide to help you learn why your check engine light might be on and what to do if it is.

Common Reasons Why Your Check Engine Light Is On

On [46 of 52] by Chris Isherwood is licensed with CC BY-SA 2.0

Your check engine light, formally known as a malfunction indicator light (MIL), is a part of your car’s on-board diagnostics (OBD) system. This system monitors and regulates the performance of your car, and it alerts you if something is wrong. If your check engine light is on, this means the OBD system detects an issue that’s actively affecting or may soon affect your engine or related systems.

Let’s take a look at some of the common causes of check engine lights turning on.

Faulty Catalytic Converter

The catalytic converter is part of your vehicle’s emission control and exhaust systems. It converts carbon monoxide and other harmful emissions from the vehicle’s exhaust into carbon dioxide and water compounds, producing emissions that are safer for the environment. However, this part may fail or become clogged, triggering your check engine light. You can help prevent catalytic converter issues by performing regular maintenance and occasionally driving long distances.

Failing Oxygen Sensor

Oxygen sensors measure how much unburnt oxygen your vehicle has in its exhaust systems. While an engine can operate with a faulty oxygen sensor, it may burn more fuel than normal. Similarly, driving with an oxygen sensor that requires replacement may cause damage to other components of your car, such as your catalytic converter or spark plugs. It’s also important to note the oxygen sensor may indicate a related oxygen or exhaust issue, reinforcing the importance of professional diagnostics for your check engine light.

Unsecure Fuel Cap

Your fuel cap is an essential part of your vehicle’s fuel delivery system. It prevents gasoline vapors from escaping the tank and, instead, recirculates them throughout your gas tank. However, if you forget to put your fuel cap back on your gas tank after filling up or if the fuel cap is otherwise missing or damaged, this may cause your check engine light to illuminate.

Leaky Mass Airflow Sensor

The mass airflow sensor determines how much fuel your engine needs to operate correctly by measuring how much air enters it. However, if there’s a leak near the sensor or along the intake tract, this may light up your check engine light. It’s important to clean the sensor and tract often because dirt, oil, or water vapor may also trigger the check engine light.

Misfiring engine

An engine misfire results from an imperfect combination of air, fuel, and compression when your vehicle’s spark plugs attempt to ignite in the combustion chamber. This may occur for a variety of reasons. Some common causes of engine misfires include:

• Bad compression.
• Defective fuel injectors.
• Defective ignition coils.
• Vacuum leaks.
• Worn spark plugs.
• Worn spark plug wires.

What To Do if Your Check Engine Light Is On

In general, it’s best to seek a professional opinion about your vehicle if your check engine light is on, even if you may feel concerned about the potentially high costs of repairs. Keep in mind some automotive centers cover these repairs under their warranties, helping you save. While it’s possible to use an OBD-II code reader or scanner to identify your issue initially, getting an expert opinion helps ensure that you address and repair the issue properly, promoting the overall quality and safety of your vehicle.

In general, it’s best to seek a professional opinion about your vehicle if your check engine light is on, even if you may feel concerned about the potentially high costs of repairs. Keep in mind some automotive centers cover these repairs under their warranties, helping you save. While it’s possible to use an OBD-II code reader or scanner to identify your issue initially, getting an expert opinion helps ensure that you address and repair the issue properly, promoting the overall quality and safety of your vehicle.

Similarly, if the light comes on and stays on while you’re driving, but you don’t notice any performance issues, this may indicate an issue with the emissions control system. This is typically a permanent failure, and it may reduce the performance of your vehicle. It’s important to seek a professional car service quickly.

There are some instances when it may be better to pull over on the side of the road and call for towing assistance. For example, if the check engine light turns on and stays illuminated and you notice performance issues, this typically suggests problems with a system or component necessary for the vehicle to function. Similarly, if the light illuminates and steadily flashes while you drive, this often indicates the engine is misfiring. Both scenarios make it dangerous to drive your car, so it’s best to pull over in a safe location and call for help.

Is It Safe To Drive if My Check Engine Light Is On?

Whether it’s safe to drive with your check engine light on depends on how the light appears and whether you notice performance issues with your vehicle. If your car seems to perform normally, it may be acceptable to drive cautiously with your light on until you reach a safe location to investigate the issue further. However, if you notice something is wrong with your vehicle’s performance, or another light turns on, it’s important to stop driving as soon as possible. Slow your vehicle and pull over in a safe spot to turn off your vehicle and call for help.

We hope this guide helps you understand some of the reasons why your check engine light comes on and what to do if this happens. If you have more questions, we encourage you to contact us. We understand it may feel stressful if your check engine line turns on, but our qualified team at AutoCenters Herculaneum is here and happy to help you.